This invention relates to methods of operating a security system and more particularly to a method for opening and changing the combination of specific security devices in the security system.
Numerous electronic security lock systems have been developed wherein specific locks are operable in response to a key coded with combination information. Such coded keys are inserted into a lock which reads and compares that information with prestored combination information in the lock. If correspondence exists, then the lock opens.
However, quite typically, in order to change the lock combination information, the individual lock combinations in each door must be reset manually by changing switches or electrical connections before a new coded key will operate the lock.
Several different approaches have been tried. For example, in one type of electronic lock system, a central console is electrically connected to each of the individual door locks. The central control unit is then used to remotely set and change the combination information for the individual locks as well as to sense a combination code on a key inserted into the lock. However, such systems are vulnerable to system failure since a failure of the central console will cause all of the locks to become inoperable. Furthermore, such systems require that each individual lock be electrically wired to the central control unit resulting in greatly increased expense particularly when retrofitting older buildings.
In another type of electronic lock system, combination information of the lock can be changed or otherwise replaced by information on the coded key inserted into the lock. For example, in Hinman et al., U.S. Pat. No. 3,860,911, a coded key actuated automatic code changing system is described whereby each lock unit includes a key decoder with a functionally assigned pair of registers containing prestored combination codes. The first register of the pair stores a current combination code. The other register of the pair stores a next or change combination code. When a key coded with both the current and the change combination codes is inserted, the current combination code carried by the key is compared with the data stored in each register. If a comparison is made with the first register or the second register an appropriate access enable signal is provided. In addition, if a comparison is made with the second register the change combination code in the second register is transferred to the first register thus becoming the current combination code; and a new next combination code, also on the key, generated in and provided for the key in a control console, is inserted in the second register. A somewhat similar code changing system is disclosed in Zucker et al., U.S. Pat. No. 3,800,284, in which combination codes are generated in the locks in correspondence with codes generated in the central station.
Still another code changing system is disclosed in Sabsay, U.S. Pat. No. 3,821,704 (reissued as U.S. Pat. No. Re. 29,259), wherein the key includes an unlock combination code and an authorization code and each lock has stored therein a combination code. If the key unlock combination corresponds to the combination code in the lock, then the lock opens. However, if the key unlock combination does not correspond to the combination code stored in the lock, the authorization code from the key is compared with the combination code from the lock. If correspondence occurs then the key unlock combination code is transferred to the lock and stored in place of the previously stored combination code.
Yet another combination changing system is disclosed in Genest et al., U.S. Pat. No. 4,213,118, wherein each code combination stored in a lock has a first and second field and each key card contains a code combination having a first and second field. When the key is inserted into the lock the two fields of the stored combination code and the combination code from the key are compared and the lock opens if correspondence exists. If correspondence does not exist then the second field of the stored combination code and the first field of the key combination code are compared. If there is correspondence at this stage an appropriate signal is generated to store the two fields of the key combination code in the lock memory in place of the two fields of the stored combination code thereby updating the combination of the lock.
In Aston, U.S. Pat. No. 4,396,914, a new combination code is generated in a lock using information from the key and from the lock. A combination code on the key is compared to the lock combination code. If there is a match, the lock opens. If there is not a match, the new combination code is generated by inverting selected bits of the lock combination code, according to information on the key. If there is a match, the new combination code replaces the lock combination code and the lock opens.
Genest et al., U.S. Pat. No. 3,926,021 (reissued as U.S. Pat. No. Re 29,846), exemplifies, along with other of the above patents, the use of differing keys (e.g., guest, maintenance and master) to address different parts of the lock memory. Ulch et al., U.S. Pat. No. 4,218,690, and Lundgren, U.S. Pat. No. 4,392,133 are also of some limited, peripheral interest.
The present invention employs key information for use in making an operation selection, from a number of available alternative selections, which is then carried out in a security device in order to determine whether combination information in the device should be changed and the device should be opened. This feature and other significant features provide important increments of additional security.